5g 450m - AP Rx Power - Sudden 20dB loss

I previously mentioned the issue in this thread. here And again in this thread. here
I already have CN Ticket 256261 open about this, but troubleshooting on Cambium’s end has stalled almost 4 weeks now.
I’m hoping someone else is seeing this issue as well. While the SM operates with 20dB less AP Power, one SM for example has a Link Test w/o Bridging of 15Mx4M 1x. And after forcing the SM to re-register, 70Mx31M 6x. It seems to have first shown up when upgrading to v16.x that had the new MU-Mimo feature for uplink.
This is happening to multiple 450m AP’s, multiple towers, multiple SM’s. The downlink Power level is always OK. Causing a re-registration (AP or SM reboot, or Drop Subscriber Session) will make the condition go away for an undetermined about of time. Usually hours. Other times the issue resolves itself without a re-registration event. Most of the affected SM’s are >2-3mi from the tower and possibly not the best LOS for them, with fresnel zone obstructions from trees, etc. But not all.
If I downgrade to a version without Mu-Mimo for uplink no problems.
Sample SM PL+SNR graph below.

Sorry for the delayed response, I have not looked into your issue before.

It seems you are using BAM, and I’m wondering if it’s causing your problems?

Is there anyone else out there using BAM? I’m curious to know because as far as I know you’re the only one I’ve heard of in years.

AAA is now the supported method. I’m wondering if we officially discontinued support for BAM but I guess not if it (mostly) works for you. I’ll check into that.

Were looking into your issue now but I’m curious on the community if anyone else is using BAM.


I inquired and we retired support for BAM around 10 years ago. In 20.3 there will be warning message on the GUI to switch to AAA. Please make a plan to migrate over.